Hi
we have recently moved houses and the drains in bath and basin in the bathroom smell really bad, only after usage.
we have tried all sorts of cleaners, had a plumber fit anti syphon traps, and the problem still exists. so far it has cost us nearly £ 400 and I am concerned the plumber is missing the real cause of the problem. We have had Dyno Rod check the drains for blockage - none found.
The Bath is along the exterior wall, so the distance is no more than 2m and the basin has it\\\'s own waste pipe ( not connected into each other). This is the main bathroom and there are additional bathrooms in the house that are not experiencing the same problem.
all help/suggestions appreciated.

The smell is coming from the accumulated muck inside the overflow and waste. Over the years you get soap scum collecting along with fats, hair, skin cells and other bodily wastes and this forms an nice warm damp place for bacteria to grow. Bacteria really are clever tenacious little chaps, believe me.

If you can't find a chemical way of cleaning it all out, perhaps a foam, I'd get a plumber to strip the lot down, give it all a good cleaning out and remake with new wastes. Then take care to give it all a good clean out with bleach or similar every couple of weeks as part of the household routine.

Thanks,
I have tried all sorts, even sulfuric acid in the overflows and drains and it is still there, worse in the mornings after use. I also tried foaming crystals.
i will try and find some sort of manual device that may get into the nooks and crannies.
It is so bad that the rest of the family refuse to use this bathroom and we need to keep the door closed so that the smell does not penetrate the rest of the house.
there is no smell when there is not water going down the drains!

RigidRaider's diagnosis makes sense to me. Smells below the traps would find it harder to get into the room than rotting scum in the overflows.

If you don't want to take it apart and scrub out the overflows yet, Boiling water and alkaline cleaners may help (some people still use Washing Soda crystals).

There are some Plughole unblockers, but they usually depend on being able to fill the trap and soak into a blockage, so they may not cling to the insides of the pipes enough. "Which" recently tested some, and found the best buys were "Drain Unblocker Sinks, Toilets, U-bends" and "Mr Muscle Active Foamer"

I'm not a plumber but it seems to me that bath oils and soaps seems to leave more deposits than detergent-like bath foams.

I have a similar problem with my sink and shower. I know what the problem is. No amount of bleach or cleaning fluid will stop it. Basically its the traps under the sink or bath. If it is the same as my problem, whenever I empty the sink it causes a vaccum of air which runs down the pip towards the shower. connected to that pipe is the shower trap which is full of water (as it should be) mean while the air which is being forced out the pipe (by the water from the sink) rushes past the shower trap causing it to suck the water from it. This leaves the trap to be momenerily empty thus leaving the pipe from the outlet sewer to the shower/sink empty. Hence the smell coming straight from the sewer pipe.

Get any of that?
To recap, emptying the sink causes vaccum which sucks the water out of the bi-passing shower trap, leaving it open to smells from the soil pipe.

Sounds like you have the same problem and I dont know why your plumber didn't spot it.